They left out the most memorable part of the battle, a unit of British medium tanks attacking German infantry. According to Wikipedia....

a group of seven of the new British Whippet medium tanks arrived. The Whippets attacked the German troops encountering some battalions "forming up in the open", doing much damage both with their machine guns and by running them down. Mitchell later remarked that when they returned their tracks were covered with blood.

It's like when the government offers tax credits for buying an electric car or putting up solar panels; the government thinks not enough people are doing this stuff, so they try to coax you into doing it.

Wargaming thinks there are not enough of these tanks driving around, and so they are providing incentives to buy them.

"In remembrance of the historical Battle of Villers-Bretonneux, World of Tanks is glad to announce the new special which is due to run through the upcoming weekend. Starting from April 20, 04:30 PDT, until April 24, 04:00 PDT (April 6, 11:30 UTC, till April 9, 11:00 UTC) the following offers will be available for all tankers:"